The present invention relates to a utilization management system of portable telephone which raises an alarm requesting a person who brings a portable telephone into a forbidden area of potable telephone, to turn off the portable telephone.
The portable telephones have been commonly used as one of the principal communication means during moving. The portable telephones, however, appear to harmfully affect various electronic apparatus due to radiation of rather strong microwave. To avoid such a harm, some areas such as airplane, hospital, and public place installed with electronic equipment, are provided with devices for raising the alarm using a loudspeaker and a notice.
Incidentally, if the holders of the portable telephones bring the portable telephones into a forbidden area with the portable telephone turned on, the loudspeaker and the notice, which are capable of urging the holders not to use the portable telephones, cannot prevent the holders from receiving a call originated by a telephone subscriber outside. Among detecting methods of holding the portable telephones in the forbidden areas, there has been available a method of detecting transmission radio wave radiated from a portable telephone which originates a call. However, the method, which is able to give an alarm through detecting the transmission radio wave emitted from the portable telephone, cannot avoid occurrence of failure in the electronic equipment; that is to say, the electronic equipment have been already affected with the transmission radio wave. Alternatively, there has been used a method of detecting a leakage radio wave radiated from the portable telephone during waiting. However, to meet regulations relevant to leakage radio wave, the portable telephones are generally shielded with tight covering, namely, does not leak radio wave outwards, or allows few radio wave to leak outside. Therefore, the conventional method could not detect leakage radio wave from the portable telephones.